For example, a multilayer ceramic capacitor is used in a variety of electronic equipment because of high reliability and low cost thereof. Specifically, information terminals, home electronics, automobile electronic components, and the like are exemplified. In particular, a multilayer ceramic capacitor for in-vehicle use is often used in a high-temperature region as compared to a multilayer ceramic capacitor used in information terminals or home electronics, and securement up to a higher-temperature region is required. For this reason, a dielectric material used in the multilayer ceramic capacitor is required to have a high specific permittivity, high specific resistance, and high voltage resistance even in the high-temperature region.
Patent document 1 discloses a dielectric ceramic composition exhibiting a high specific permittivity at room temperature and having high specific resistance even in a high-temperature range of 180° C. Specifically, disclosed is a technology relating to a multilayer ceramic capacitor using a dielectric ceramic composition containing, as a main component, a tungsten bronze type composite oxide represented by a composition formula (K1−yNay)Sr2Nb5O15 (provided that, 0≤y<0.2) and containing a first sub component and a second sub component in 0.1 part by mol or more and 40 parts by mol or less with respect to 100 parts by mol of the main component.
However, as understood from the composition formula, in the patent document 1, potassium (K) and sodium (Na) that are alkali metal elements are contained as constituent elements of the main component. Since the alkali metal has high volatility, there is a problem in that handling at the time of manufacturing is prone to be cumbersome, for example, a process of filling an alkali metal element needs to be introduced in processes.
Further, when the alkali metal with high volatility is contained, there are problems in that a lattice defect caused by the alkali metal easily occurs in the dielectric composition by a binder removal process and a firing process that perform a heat treatment at a high temperature, or a reoxidation process, and high voltage resistance is difficult to obtain. Therefore, in the patent document 1, there is no disclosure of a technology relating to a high specific permittivity and high voltage resistance in the high-temperature region.
Further, patent document 2 discloses a technology relating to a ceramic capacitor which includes a dielectric ceramic layer obtained by adding a plurality of additives to a perovskite type oxide formed by a composition formula (Ca1−x(Ba,Sr)x)k(Zr1−yTiy)O3 having a high quality factor Q at 20° C., a favorable temperature coefficient, and high voltage resistance at 150° C.
In the patent document 2, high voltage resistance is exhibited in a high-temperature region of 150° C., but there are problems in that the specific permittivity at 20° C. is only about 125 at a maximum and a desired capacitance is difficult to obtain in a high-temperature region of 175° C. or higher that is expected to be used hereafter.
Further, non-patent document 1 discloses a technology relating to a tungsten bronze type dielectric Ba2MTi2Nb3O15 (M=Bi3+, La3+, Nd3+, Sm3+, Gd3+) with a high specific permittivity and a small dielectric loss. The tungsten bronze type dielectric has a high specific permittivity at room temperature of about 100 to 700 and a favorable value of tan δ at room temperature of 5% or less. In addition, non-patent document 2 discloses a technology relating to a tungsten bronze type dielectric Ba2Sm2Ti4Ta6O30 with a high specific permittivity and a small dielectric loss. The tungsten bronze type dielectric has a high specific permittivity at room temperature of about 120 and a favorable value of tan δ at room temperature of 3% or less. However, the non-patent document 1 has a problem in that a change ratio of the specific permittivity at 200° C. to the specific permittivity at room temperature is large.